OpenSSL Security Advisory

[Mark J Cox]

I just spotted it via twitter, https://raccoon-attack.com/

Mark

On Wed, Sep 9, 2020 at 2:08 PM Dmitry Belyavsky <beldmit at gmail.com> wrote:
>
> Could you please let me know when it is available?
>
> On Wed, Sep 9, 2020 at 3:51 PM Mark J Cox <mark at openssl.org> wrote:
>>
>> They should be releasing their paper very soon (today).
>>
>> Regards, Mark
>>
>> On Wed, Sep 9, 2020 at 1:45 PM Dmitry Belyavsky <beldmit at gmail.com> wrote:
>> >
>> > Is the description of the attack publicly available?
>> >
>> > On Wed, Sep 9, 2020 at 3:39 PM OpenSSL <openssl at openssl.org> wrote:
>> >>
>> >> -----BEGIN PGP SIGNED MESSAGE-----
>> >> Hash: SHA512
>> >>
>> >> OpenSSL Security Advisory [09 September 2020]
>> >> =============================================
>> >>
>> >> Raccoon Attack (CVE-2020-1968)
>> >> ==============================
>> >>
>> >> Severity: Low
>> >>
>> >> The Raccoon attack exploits a flaw in the TLS specification which can lead to
>> >> an attacker being able to compute the pre-master secret in connections which
>> >> have used a Diffie-Hellman (DH) based ciphersuite. In such a case this would
>> >> result in the attacker being able to eavesdrop on all encrypted communications
>> >> sent over that TLS connection. The attack can only be exploited if an
>> >> implementation re-uses a DH secret across multiple TLS connections. Note that
>> >> this issue only impacts DH ciphersuites and not ECDH ciphersuites.
>> >>
>> >> OpenSSL 1.1.1 is not vulnerable to this issue: it never reuses a DH secret and
>> >> does not implement any "static" DH ciphersuites.
>> >>
>> >> OpenSSL 1.0.2f and above will only reuse a DH secret if a "static" DH
>> >> ciphersuite is used. These static "DH" ciphersuites are ones that start with the
>> >> text "DH-" (for example "DH-RSA-AES256-SHA"). The standard IANA names for these
>> >> ciphersuites all start with "TLS_DH_" but excludes those that start with
>> >> "TLS_DH_anon_".
>> >>
>> >> OpenSSL 1.0.2e and below would reuse the DH secret across multiple TLS
>> >> connections in server processes unless the SSL_OP_SINGLE_DH_USE option was
>> >> explicitly configured. Therefore all ciphersuites that use DH in servers
>> >> (including ephemeral DH) are vulnerable in these versions. In OpenSSL 1.0.2f
>> >> SSL_OP_SINGLE_DH_USE was made the default and it could not be turned off as a
>> >> response to CVE-2016-0701.
>> >>
>> >> Since the vulnerability lies in the TLS specification, fixing the affected
>> >> ciphersuites is not viable. For this reason 1.0.2w moves the affected
>> >> ciphersuites into the "weak-ssl-ciphers" list. Support for the
>> >> "weak-ssl-ciphers" is not compiled in by default. This is unlikely to cause
>> >> interoperability problems in most cases since use of these ciphersuites is rare.
>> >> Support for the "weak-ssl-ciphers" can be added back by configuring OpenSSL at
>> >> compile time with the "enable-weak-ssl-ciphers" option. This is not recommended.
>> >>
>> >> OpenSSL 1.0.2 is out of support and no longer receiving public updates.
>> >>
>> >> Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2w.  If
>> >> upgrading is not viable then users of OpenSSL 1.0.2v or below should ensure
>> >> that affected ciphersuites are disabled through runtime configuration. Also
>> >> note that the affected ciphersuites are only available on the server side if a
>> >> DH certificate has been configured. These certificates are very rarely used and
>> >> for this reason this issue has been classified as LOW severity.
>> >>
>> >> This issue was found by Robert Merget, Marcus Brinkmann, Nimrod Aviram and Juraj
>> >> Somorovsky and reported to OpenSSL on 28th May 2020 under embargo in order to
>> >> allow co-ordinated disclosure with other implementations.
>> >>
>> >> Note
>> >> ====
>> >>
>> >> OpenSSL 1.0.2 is out of support and no longer receiving public updates. Extended
>> >> support is available for premium support customers:
>> >> https://www.openssl.org/support/contracts.html
>> >>
>> >> OpenSSL 1.1.0 is out of support and no longer receiving updates of any kind.
>> >> The impact of this issue on OpenSSL 1.1.0 has not been analysed.
>> >>
>> >> Users of these versions should upgrade to OpenSSL 1.1.1.
>> >>
>> >> References
>> >> ==========
>> >>
>> >> URL for this Security Advisory:
>> >> https://www.openssl.org/news/secadv/20200909.txt
>> >>
>> >> Note: the online version of the advisory may be updated with additional details
>> >> over time.
>> >>
>> >> For details of OpenSSL severity classifications please see:
>> >> https://www.openssl.org/policies/secpolicy.html
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>> >> -----END PGP SIGNATURE-----
>> >
>> >
>> >
>> > --
>> > SY, Dmitry Belyavsky
>
>
>
> --
> SY, Dmitry Belyavsky